The present invention is a process for reacting organodisilanes with organic halides to form monosilanes. The process comprises heating a mixture comprising an organodisilane and an organic halide at a temperature within a range of about 100.degree. C. to 350.degree. C. The process is especially useful for reacting alkenyl chlorides, such as allyl chloride, with organodisilanes to form monosilanes having alkenyl substitution. The process is also useful for converting a high-boiling organodisilane containing fraction from a direct process for forming organosilanes into more useful monosilanes.
The primary commercial method for producing organosilanes involves the reaction of an organic halide with elemental silicon. After the desired organosilanes have been recovered from the product mixture by distillation there remains a high-boiling residue which comprises among other components organodisilanes. Since these organodisilanes have very little commercial value it is desirable to convert them to the more useful monosilanes. The present invention relates to a process for converting organodisilanes to organomonosilanes by heating a mixture comprising an organodisilane and an organic halide at a temperature within a range of about 100.degree. C. to 350.degree. C. In the process the Si-Si bond of the organodisilane is broken resulting in the formation of two monosilanes, with the organic group of the organic halide substituting on one of the silicon atoms and the halogen group of the organic halide substituting on the other silicon atom.
Mohler et al., U.S. Pat. No. 2,598,435, describe a process where an organohalopolysilane containing a silicon-silicon linkage is heated at an elevated temperature to rupture the silicon-silicon bond and obtain a material of lower molecular weight.
Barry et al., U.S. Pat. No. 2,474,087, teach the reaction between an organic halide and a polyhalopolysilane such as hexachlorodisilane can be carried out at a temperature between 100.degree. C. and 450.degree. C. Barry et al. make no reference to organohalodisilanes.
Barry et al., U.S. Pat. No. 2,681,355, teach that when organohalodisilanes are cracked by the heat method of Mohler et al., supra, extensive coking of the reactor takes place. Barry et al., suggest this coking can be eliminated by the addition of hydrogen chloride to the process.
Numerous other methods have been reported where the heat cracking of organodisilanes is conducted in the presence of other compounds to facilitate the reaction and avoid the coking problem described by Barry et al., supra.
Kuriyagawa et al., U.S. Pat. No. 2,787,627, teach a method where a solution of trimethyltriethyldisilane was diluted in ethyl bromide and made to react upon the addition of dry bromine to the process along with refluxing.
Atwell et. al., U.S. Pat. No. 3,772,347, describe a process were organochlorodisilanes are reacted with an organic chloride in the presence of a transition metal complex comprising palladium and phosphorous.
Halm et al., U.S. Pat. No. 4,962,219, describe a process where an organohalodisilane is contacted with an organic halide in the presence of a metal, such as aluminum, which serves as a halogen acceptor, at a temperature greater than about 150.degree. C.
The present inventors have unexpectedly discovered that a mixture comprising an organic halide and an organodisilane can be heated at a temperature within a range of about 100.degree. C. to 350.degree. C. to form monosilanes. In the present process coking does not occur and catalysts and other reactive compounds as described in the cited art are not required.